Spiral liquid cooled baffle for shielding diffusion pumps



SPIRAL LIQUID COOLED BAFF'LE FOR SHIELDING DIFFUSION PUMPS Original Filed Aug. 10, 1962 2 Sheets-Sheet 1 INVENTOR. CHARLES B. HOOD, JR.

XMMQJQ ATTORNEYS May 30, 1967 c. B. HOOD, JR

2 Sheets-$heet :1

Original Filed Aug. 10, 1962 1 f W m B 1 2 0 a V\ L 6 6 m v 8 A Q 4 m w ATTORNEYS United States Patent 3,321,927 SPIRAL LIQUID COULED RAFFLE FOR SHIELDING DIFFUSION PUMPS Charles B. Hood, Jr., 2850 Canterbury Road, Columbus, Ohio 4-3221 Continuation of appiication Ser. No. 216,084, Aug. 10, 1962. This application Feb. 12, 1965, Ser. No. 438,815 8 Claims. (Cl. 62-555) This application is a continuation of my co-pending application Ser. No. 216,084 filed Aug. 10, 1962, now abandoned.

This invention relates generally to space simulation chambers and particularly to an improved cryogenically cooled baffle construction for shielding the interior of such chambers from radiation from diffusion pumps used to evacuate such chambers.

In general, space simulation chambers are employed in the space vehicle program to simulate the cold black environment of outer space. In construction, they include an outer structural wall means which forms a sealed chamber that is evacuated by a diffusion pump. A thermal shroud in the form of refrigerated walls is suspended within said outer structural Wall means to provide a heat sink that directly surrounds a test specimen location. The refrigerated walls forming the thermal shroud are cooled by conduits in the form of metal tubes through which are pumped flows of cryogenic gas.

In instances where gaseous helium is used as a refrigerant the thermal shroud temperatures are in the range of to degrees Kelvin.

A typical outer structural wall and thermal shroud construction for a space simulation chamber are illustrated and described in detail in co-pending application Ser. No. 216,625 filed Oct. 31, 1962, now US. Patent No. 3,273,636.

A bafile means that is cryogenically cooled is located within the passage leading to the diffusion pump to provide a cold wall for insulating the test specimen within the shroud from radiation from the inlet of the diffusion pump. The cold balfie means is cooled by an annular manifold for conducting a flow of refrigerant in the form of a cryogenic gas such as liquid nitrogen. This bafile means is also optically tight and provides a cold pervious wall that can be refrigerated to the low range of 300 degrees F. to effectively shield the inlet of the diffusion pump from the interior of the thermal shroud.

The conduit leading to the inlet of the diffusion pump is also provided with a novel spiral water-cooled baffle means that forms an optically insulated cool wall which protects the previously mentioned liquid nitrogen cooled baflle means from direct radiation from the hot inlet of the diffusion pump.

It is, therefore, an object of the present invention to provide an improved cryogenic bafiie construction that efiiciently shields the interior of a space simulation chamber from the hot radiation from a diffusion pump.

It is another object of the present invention to provide an apparatus of the type described that incorporates an optically tight bafile wall that prevents oil from a diffusion pump from migrating up into the confines of the thermal shroud.

It is another object of the present invention to provide a baffle construction that permits operation of a diffusion pump at pressures above pressures existing within the confines of the thermal shroud.

It is another object of the present invention to provide an improved baffle construction that incorporates a novel Water-cooled spiral baffle adapted to shield the main liquid nitrogen cooled baffle means from direct radiation from the hot inlet to the diffusion pump.

3 ,3 1,927 Patented May 30, 1967 It is another object of the present invention to provide an improved bafiie construction that incorporates a spiral bafile the entire area of which is cooled by a single continuous conduit whereby the need for fabricating conduit junctions for a plurality of conduit segments is eliminated.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawings:

FIG. 1 is a broken perspective view of a typical space simulation chamber that incorporates the baffie construction of the present invention;

FIG. 2 is a side sectional view showing the apparatus of FIG. 1; and

FIG. 3 is an enlarged view of a liquid nitrogen cooled baffle and spiral water cooled baffle assembly construction in accordance with the present invention.

Referring in detail to the drawings, a space simulation chamber is indicated generally at 20 and includes an outer structural wall 22 that forms a sealed chamber 24, said chamber being evacuated by a diffusion pump the intake of which is indicated at 26 and includes an inlet conduit 27 and a cover member 2? spaced from said conduit. Conduit 27 extends axially of the flow through said housing means and cover member 29 extends laterally of said flow.

A thermal shroud indicated generally at 28 is mounted within structural wall 22 and includes a refrigerated wall 30 that is cooled by conduit means in heat exchange relationship with the wall that carries a flow of helium gas.

Thermal shroud 28 is suspended within the container means by appropriate structure of the type described in detail in co-pending application 216,625 filed Oct. 31, 1962.

As is best seen in FIG. 2, the bottom of the thermal shroud 28 includes a radiation shield indicated generally at 32 that comprises side frame member 34 that supports a plurality of transverse laterally spaced bafiie members 36 of V-shaped cross section, said cross sectional configuration being illustrated in FIG. 2.

The apex of each baffle member 36 is disposed between the legs of the next adjacent member in optical tight relationship so as to optically insulate the interior of chamber 24 from diffusion pump inlet 26.

A conduit 38 connects the interior of space chamber 20 with the previously mentioned inlet 26 of the diffusion pump and includes an inlet portion in which is mounted a liquid nitrogen cooled bafile means indicated generally at 40 that comprises an annular manifold 42.

Inlet conduit 44 is connected to manifold 42 at a fitting 46 and passes outwardly through the wall of conduit 38 at a fitting 48. The outer end of inlet conduit 44 is connected to a conventional dewar, not illustrated, containing a supply of liquid nitrogen.

The flow of liquid nitrogen is released from manifold 42 via a conduit 54 that is connected to the manifold at a fitting 52 and which passes outwardly through the wall 33 of the conduit at a fitting 43.

As is best seen in FIG. 3, manifold 42 is mounted to the conduit wall 38 by an annular hanger bracket 54.

Referring again to FIG. 1, a water-cooled spiral bafile means is mounted between liquid nitrogen cooled baflle and the inlet 26 of the diffusion pump and is indicated generally at 69.

The spiral baffle means 60 comprises a narrow continuous strip of metal, such as copper or the like, that is preferably cut from sheet stock and stretched out to the configuration seen in FIGS. 1 and 3.

This spiral strip of metal is indicated at 62 and is sup ported by a rack formed by a plurality of inclined members at, the inner edges of which are provided with notches 66 that form horizontal edges that support :strip -52.

As is seen in FIG. 3, inclined members 64 are mounted to the cylindrical wall 38 of the conduit by a plurality of inwardly extending brackets 70.

The spiral metal strip is cooled by a continuous length of tubing 72 mounted on the upper surface thereof for conducting a fiow of coolant, such as water, in heat exchange relationship with the strip. Hence the coolant for the spiral metal strip 62 is obtained merely by connecting one end of tubing 72 to a water tap and the other end of the tubing to drain.

Coolant conduit 7 2 includes inlet portion 74 and outlet portion 76 that connect the spiral tube 72 with a coolant circulation system not illustrated.

It is important to point out that cover member 29 is disposed across the small end of spiral baffle means 60 so as to insulate the path through the spiral battle means from radiation and vapor from inlet conduit 27.

In operation, a test specimen indicated generally at 10, which may be in the form of a space vehicle, or other object to be tested, is supported within the confines of thermal shroud 28, as seen in FIG. 2.

The space chamber 2% is cooled down by a cryogenic refrigerator which supplies a flow of refrigerant, such as liquid nitrogen, in heat exchange relationship With the thermal shroud 28 which functions as a heat sink for absorbing radiant energy from test specimen 10.

The interior of the space chamber is evacuated by operating the diffusion pump, the inlet of which is illustrated at 26.

It should be stated generally that diffusion pumps used for evacuating space chambers operate on the oil jet principle and at oil vapor pressures in the neighborhood of 1 10 millimeters of mercury at the pump. By incorporating the baffle construction of the present inven tion, it is possible to operate the system with a pressure differential between the pump and the chamber 24 within the shroud such that the pump operates at a higher pressure than the extremely low pressure value required within the space chamber.

When the diffusion pump is being operated, the nitrogen cooled baiile means 4% provides a thermal shield at a temperature in the order of -3OO degrees F. to provide a cold wall that insulates the space chamber and test specimen from the hot inlet 26 of the diffusion pump.

Spiral bathe means '65) is operated by circulating water through the spirally wound tube 74 in heat exchange relationship with the spiral metal strip 62, the latter serving to optically insulate the cold nitrogen cooled battle means 4t) from radiation from the hot intake 26 of the diffusion pump.

It should be pointed out that the spirally extending metal strip 62 is arranged so that the inner edge of each coil overlaps the outer edge of the next preceding coil to optically insulate said spiral bafile means from radiation from inlet 26 of the diliusion pump.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

I claim:

1. An improved bafile apparatus for shielding the interior of a cryogenically cooled chamber from the inlet of a diffusion pump, said apparatus comprising in combination a diffusion pump; housing means forming a longitudinally extending passage for connecting the interior of said chamber with said diffusion pump; a diffusion pump inlet including an inlet conduit extending axially of the flow through said housing means and a cover member spaced from said conduit and extending laterally of the flow through said housing means; a. first bafile means mounted in said housing means and comprising a plurality of laterally spaced baffle members disposed in overlapping optical tight relationship so as to optically insulate the interior of said chamber from said diffusion pump; cooling conduit means for a flow of a liquilied cryogenic gas in heat exchange relationship with said first baffle means; a second battle means mounted in said housing means between said first 'baffie means and said diffusion pump, said second b aille means including a spiral member and a spiral cooling conduit mounted on said spiral member, said spiral member including succcssive coils disposed in overlapping optical tight relationship so as to optically insulate said first baflle means from radiation from said inlet of said diffusion pump; reservoir means for a supply of cryogenic fluid connected to said cooling conduit means; and a second reservoir means for a supply of warmer coolant connected to said spiral cool ing conduit, said cover member of said diffusion pump inlet being disposed across the small end of said spiral member so as to insulate the path through said spiral member to said first bafile means from vapor and radiation from said difiusion pump.

2. The bafile apparatus defined in claim 1 wherein said bafile members of said first bafl'le means are of V-shaped cross section and wherein the apex of each member is extended between the legs of the next adjacent member to provide said optical tight relationship.

3. The bafile apparatus defined in claim 1 wherein said cooling conduit for said first bafile means is in the form of an annular chamber surrounding said baflle members.

4. The baffle apparatus defined in claim ll wherein said bafile members of said first baffle means are of V-shaped cross section and wherein the apex of each member is extended between the legs of the next adjacent member to provide said optical tight relationship; and wherein said cooling conduit for said first baflie means is in the form of an annular chamber surrounding said baffle members.

5. An improved bame apparatus for shielding the interior of a cryogenically cooled chamber from the inlet of a diffusion pump, said apparatus comprising in combination a diffusion pump; housing means forming a longitudinally extending passage for connecting the interior of said chamber with said diffusion pump; a diffusion pump inlet including an inlet conduit extending axially of the flow through said housing means and a cover member spaced from said conduit and extending laterally of the flow through said housing means; a first bafile means mounted in said housing means and comprising a plurality of laterally spaced bafile members disposed in overlapping optical tight relationship so as to optically insulate the interior of said chamber from said diffusion pump; cooling conduit means for a flow of a liquified cryogenic gas in heat exchange relationship with said first bafiie means; a second baffle means mounted in said housing means between said first bafiie means and said diffusion pump, said second baffle means including a spiral member and a spiral cooling conduit mounted on said spiral member, said spiral member including successive coils disposed in overlapping optical tight relationship so as to optically insulate said first baffle means from radiation from said inlet of said ditfusion pump; a radiation shield located between said first bafile means and the interior of said chamber; reservoir means for a supply of cryogenic fluid connected to said cooling conduit means; and a second reservoir means for a supply of warmer coolant connected to said spiral cooling conduit, said cover member of said diffusion pump inlet being disposed across the small end of said spiral member so as to insualte the path through said spiral member to said first bathe means from vapor and radiation from said diffusion pump.

6. The baffle apparatus defined in claim 5 wherein said bafile members of said first bafile means are of V-shaped Cross section and wherein the apex of each member is 6 extended between the legs of the next adjacent member 3,075,688 1/1963 Erhart et al 230-101 to provide said optical tight relationship. 3,075,689 1/ 1963 Stevenson 230101 7.The bafile apparatus defined in claim 5 wherein said 3,081,068 3/1963 Milleron 62 cooling conduit for said first bafile means is in the form 3,102,678 9/1963 Levenson 230-101 of an annular chamber surrounding said baffle members. 5 3,117,714 1/1964 Aupoix 230101 8. The bafiie apparatus defined in claim 5 wherein said 3,122,896 3/ 1964 Hickey 230-69 X baffle members of said first bafile means are of V-shaped 3,137,551 6/1964 Mark 62-268 X cross section and wherein the apex of each member is extended between the legs of the next adjacent member FOREIGN PATENTS to provide said optical tight relationship; and wherein 10 47,011 8/1936 Francesaid cooling conduit for said first bafiie means is in the 765,973 11/1936 Franceform of an annular chamber surrounding said baflle 1,028,734 4/ 1958 Germanymembers. 1,037,644 8/ 1958 Germany. 1,066,703 10/1959 Germany. References Cited 15 773,465 4/ 1957 Great Britain. UNITED STATES PATENTS Bntam- 1,595,286 8/1926 Petten et a1 55-17 137983 10 /1960 j Y Q 2,080,421 5/1937 Hickman 230-101 2,112,037 3/1938 Malter 230101 OTHER REFERENCES 2125910 8/1938 Gardner 23O101 X Ul-lman, Ralph: A Large Metal System Permitting Low 212911054 7/1942 Nelsor} 230401 Base Pressures, University of California, Radiation Lab., 2,386,298 10/1945 Downlng et a1 230401 Livermore Site, Livermore, Calif, Document No. UCRL 2,437,849 3/1948 Cox et al 230-101 4972 Oct 4 1957 7pages 2,703,673 3/1955 Winkler 230--101 25 2,865,560 12/1958 Franceschini 230'-101 3,010,285 11/1961 Penn 62*100 X HARRY B. THORNTON, Przmary Examine). 3 027, 51 4 19 2 Nerge 230 9 D. TALBERT, Assistant Examiner. 

1. AN IMPROVED BAFFLE APPARATUS FOR SHIELDING THE INTERIOR OF A CRYOGENICALLY COOLED CHAMBER FROM THE INLET OF A DIFFUSION PUMP, SAID APPARATUS COMPRISING IN COMBINATION A DIFFUSION PUMP; HOUSING MEANS FORMING A LONGITUDINALLY EXTENDING PASSAGE FOR CONNECTING THE INTERIOR OF SAID CHAMBER WITH SAID DIFFUSION PUMP; A DIFFUSION PUMP INLET INCLUDING AN INLET CONDUIT EXTENDING AXIALLY OF THE FLOW THROUGH SAID HOUSING MEANS AND A COVER MEMBER SPACED FROM SAID CONDUIT AND EXTENDING LATERALLY OF THE FLOW THROUGH SAID HOUSING MEANS; A FIRST BAFFLE MEANS MOUNTED IN SAID HOUSING MEANS; A FIRST PRISING A PLURALITY OF LATERALLY SPACED BAFFLE MEMBERS DISPOSED IN OVERLAPPING OPTICAL TIGHT RELATIONSHIP SO AS TO OPTICALLY INSULATE THE INTERIOR OF SAID CHAMBER FROM SAID DIFFUSION PUMP; COOLING CONDUIT MEANS FOR A FLOW OF A LIQUIFIED CRYOGENIC GAS IN HEAT EXCHANGE RELATIONSHIP WITH SAID FIRST BAFFLE MEANS; A SECOND BAFFLE MEANS MOUNTED IN SAID HOUSING MEANS BETWEEN SAID FIRST BAFFLE MEANS AND SAID DIFFUSION PUMP, SAID SECOND BAFFLE MEANS INCLUDING A SPIRAL MEMBER AND A SPIRAL COOLING CONDUIT MOUNTED ON SAID SPIRAL MEMBER, SAID SPIRAL MEMBER INCLUDING SUCCESSIVE COILS DISPOSED IN OVERLAPPING OPTICAL TIGHT RELATIONSHIP SO AS TO OPTICALLY INSULATE SAID FIRST BAFFLE MEANS FROM RADIATION FROM SAID INLET OF SAID DIFFUSION PUMP; RESERVOIR MEANS FOR A SUPPLY OF CRYOGENIC FLUID CONNECTED TO SAID COOLING CONDUIT MEANS; AND A SECOND RESERVOIR MEANS FOR A SUPPLY OF WARMER COOLANT CONNECTED TO SAID SPIRAL COOLING CONDUIT, SAID COVER MEMBER OF SAID DIFFUSION PUMP INLET BEING DISPOSED ACROSS THE SMALL END OF SAID SPIRAL MEMBER SO AS TO INSULATE THE PATH THROUGH SAID SPRIAL MEMBER TO SAID FIRST BAFFLE MEANS FROM VAPOR AND RADIATION FROM SAID DIFFUSION PUMP. 